Iris type diaphragm



Jan. 6, 1970 n. M. PETERSON ET AL 3,487,762

IRIS TYPE DIAPHRAGM Filed May 17, 1967 DEAN M- PETERSON WILLIAM WINDLEJR' INVENTORS ATTORNEYS United States Patent O [1.8. Ci. 95-64 14 ClaimsABSTRACT OF THE DISCLOSURE An iris type diaphragm including a singleone-piece blade member having several overlapping diaphragm bladesmovably supported by flexible elements integral therewith, andcooperating in equiangular radial relation to one another to define asymmetrically variable aperture. The blade member is positioned in asupport ring, and the blades are mounted on an adjustable disk rotatablewithin the support ring.

BACKGROUND OF THE INVENTION The present invention relates to adjustableiris type diaphragms, particularly for use in photographic cameras andother types of optical apparatus, and more specifically to suchdiaphragms including a plurality of diaphragm blades movably supportedby flexible means integral therewith, such blades preferably comprisinga single onepiece blade member.

In the photographic and optical arts it is Well known to employadjustable diaphragms to vary selectively the effective aperture of alens system, and it has long been recognized that, ideally, any aperturedefined by such an adjustable diaphragm should be perfectly circular andconcentric with the axis of the lens system. With a diaphragm that isadjustable infinitely over a given range of aperture sizes, it isimpossible, for practical purposes, to preserve perfect aperturecircularity; but such circular apertures can be satisfactorilyapproximated by an adjustable diaphragm in which at least threediaphragm blades, and preferably more, are pivoted at equiangular pointsof a circle concentric with the lens axis and are moved in unison by anadjusting ring so that the inner edges of the overlapping blades definea variable substantially circular aperture along the lens axis. As usedherein, this general type of diaphragm is referred to as an irisdiaphragm, implying its close resemblance to the related structure ofthe human eye.

Iris type diaphragms are employed commonly in more expensive cameras,but, as presently made, are relatively costly do to the number of partsthat must be fabricated and assembled, which may include as many as tenor more diaphragm blades in each iris diaphragm assembly. Therefore, inmost relatively inexpensive cameras provided with an infinitely variablediaphragm device, the advantages of an iris type diaphragm aresacrificed in the interest of economy by substituting a variablediaphragm comprising fewer parts, typically one in which two overlappingmovable blades are provided with angular notches which cooperate todefine a generally rectangular aperture of variable area.

SUMMARY OF THE INVENTION The present invention is directed tosimplifying and thereby reducing the cost of iris diaphragms to enablethem to be employed economically in relatively inexpensive cameras. Thisobjective is realized, in accordance with the present invention, byeliminating the mounting pins or the like customarily used to supportthe diaphragm blades in movable fashion and, preferably, by combining3,487,762 Patented Jan. 6, 1970 all of the diaphragm blades in a singleone-piece blade member. To assemble the preferred diaphragm structure,the one-piece blade member is positioned in a support ring; an adjustingdisk is positioned in engagement with the blades of the blade member;and the support ring is attached to a mounting plate to retain theforegoing components in assembled relation. Thus, the complete irisdiaphragm unit comprises only four basic components, as opposed to themany more components of a corresponding conventional iris diaphragmassembled from separate blades, pivot pins, etc. Additionally, by virtueof this novel construction, the accuracy and reliability of theassembled unit is much less dependent on critical tolerances than in thecase of corresponding conventional devices, thereby further simplifyingthe manufacturing process.

BRIEF DESCRIPTION OF THE DRAWINGS Various means for accomplishing theinvention will be apparent from the following detailed description of aspecific preferred embodiment thereof, reference being made to theaccompanying drawings in which like reference numerals denote likeelements and in which:

FIG. 1 is an exploded perspective view of a complete diaphragm unitaccording to a preferred embodiment of the invention, with thecomponents thereof shown in horizontal positions;

FIG. 2 is an enlarged perspective view of the blade member comprisingone component of the diaphragm unit illustrated in FIG. 1;

FIG. 3 is an enlarged view of the assembled diaphragm unit,corresponding to a top view of the assembled components positionedhorizontally as depicted in FIG. 1, with the diaphragm bladesillustrated in closed position; and

FIG. 4 corresponds to FIG. 3 and illustrates the diaphragm bladesadjusted to an open position.

DETAILED DESCRIPTION Referring first to FIG. 1, the four basiccomponents of the subject iris diaphragm unit comprise support ring 11,blade member 12, adjusting disk 13 and mounting plate 14. The blademember 12 is illustrated most clearly in FIG. 2, and comprises a strapmember 15 provided with cars 16 and 17 at its opposite ends. A pluralityof substantially identical curved diaphragm blades 18, are supportedalong strap 15 in uniformly spaced relation by correspondingsubstantially identical support arms 19 integrally joined to the topedge of the strap as viewed in FIGS. 1 and 2, with the free ends of theblades being provided respectively with holes 21. As should be apparentby reference to FIG. 2, the blade member 12 can be formed veryinexpensively from a stamped sheet metal blank simply by bending overthe support arms 19 where they join strap member 15 and by forming rightangles bends at the intersections of the blades 18 and their respectivesupport arms 19 so that the blades lie in perpendicular relation tosupport strap 15.

To assemble the diaphragm unit, strap member 15 is bowed into a circlewith the blades 18 pointed inwardly, as shown in FIG. 1, and is slippedupwardly into opening 22 in support ring 11, with the adjacent ears 16and 17 received by notch 23 and with the support arms 19 accommodated bycorresponding substantially identical slots 24. The adjusting disk 13 isthen positioned immediately below blade member 12 with its circularportion 25 received in opening 22 and with lever arm 26 extendingoutwardly through recess 27 of support ring 11. As adjusting disk 13 ismoved into this position it is oriented so that its upwardly projectingdiaphragm control pins 28 enter the corresponding holes 21 in thediaphragm blades 18, which can be moved slightly, if necessary, to alignthe holes with the respective pins. To complete the assembly operation,mounting plate 14 is located adjacent the bottom surfaces of supportring 11 and adjusting disk 13 and is held in place by screws 29 threadedinto holes 31 in the support ring. When the unit is so assembled, axialmovement of blade member 12 is limited by adjusting disk 13 and byinwardly extending projections 32 on support ring 11 located adjacentthe upper edge surface of strap 15. Rotatable movement of blade member12 is prevented by the reception of ears 16 and 17 in notch 23 (seeFIGS. 3 and 4). Accordingly, the blades 18 are maintained in adjacentrelation to adjusting disk 13 with the resiliency of the blades servingto maintain them in engagement with the diaphragm control pins 28,thereby eliminating the need to rivet the pins or to employ equivalentmeans to retain the blades in engagement therewith.

When blade member 12 is bowed into circular form, the support arms 19thereof extend tangentially from strap member 15, whereby the diaphragmblades 18 are positioned in the overlapping relation shown in FIGS. 1and 3. As long as the blades are so positioned, they cooperate toobscure completely the circular adjusting ring opening 33, which isaligned with a larger central hole 34 in mounting plate 14 and definesthe maximum effective aperture of the lens system with which thediaphragm unit is coaxially associated. However, as lever 26 is moved ina clockwise direction, the diaphragm blades 18 move outwardly in unison,by flexing the respective support arms 19, which are somewhat narrowerand hence more flexible than strap 15. Accordingly, the aperture definedby blades 18 along the axis of the unit is enlarged progressively untillever 26 reaches the end of recess 27, as illustrated in FIG. 4, atwhich time the blades are positioned slightly beyond opening 33. Bycomparison of FIGS. 3 and 4, it will be recognized that a relativelysmall aperture defined by the blades is of generally rectangularsymmetrical shape, but that the aperture progressively assumes a morenearly circular shape as its size increases. Therefore, this structureadmittedly does not satisfy entirely the objective of maintaining acircular aperture at all times, but provides a substantially bettercompromise than can be achieved with conventional inexpensive diaphragmdevices comprising only two movable blades, particularly at largeraperture openings at which the circularity of the aperture is generallyof greater significance. However, it should be understood that thedepicted four blade diaphragm unit is only illustrative and that agreater number of blades could be provided along the strap member andassociated with corresponding control pins on the adjusting disk,whereby the aperture would more closely approximate a circle at alltimes, as in the case of conventional iris type diaphragm. While thenumber of blades that can be attached to the strap is limited by thelength of the support arms in the illustrated embodiment, it should alsobe apparent that other blade support means could be provided to enable agreater number of blades to be attached movably to the strap, eg bymolding the entire unitary blade member from a flexible material such aspolypropylene, with the blades being attached to the strap by integrallymolded hinge portions.

Although FIG. 3 illustrates the blades 18 positioned to obscurecompletely the opening 33 in disk 13, it is obvious that when the unitis employed as a variable iris diaphragm in a camera, the lever normallywill be blocked by an edge of recess 27 at a position slightly clockwisefrom that shown, so that the blades will define an aperture ofpredetermined minimum size. However, the completely closed condition ofthe unit shown in FIG. 3 is illustrative of the fact that the same typeof structure can also serve as a shutter or similar device in a cameraor other instrument.

It should also be noted that the resiliency of the support arms 19 urgesthe blades 18 toward their respective positions shown in FIG. 3, therebyeliminating the need for supplemental springs or the like inapplications requiring this mode of resiliently biased Operation, e.g.in using the unit as a normally closed shutter or as a variablediaphragm adapted to close automatically to a predetermined aperturesetting. Similarly, by permanently bending the support arms 19, theblades 18 could be biased thereby toward the respective positions inwhich they define the maximum diaphragm aperture or any selectedintermediate aperture.

Although the foregoing description relates to a specific embodiment ofthe invention, it is obvious that variations and modifications thereofcan be effected Within the spirit and scope of the invention.Accordingly, the present disclosure is to be considered as illustrativeand not as limiting the scope of the invention which is defined by thefollowing claims.

We claim:

1. An iris type diaphragm unit comprising:

a unitary one-piece diaphragm member including a peripheral strapmember, a plurality of blade members extending inwardly from saidperipheral strap member in overlapping relation to one another, andflexible blade support means at one end of each of said blade membersattaching said one end to said strap member;

a blade adjusting member adjacent said blade members and including meansengageable with portions of said blades spaced from said support meansfor moving in unison said portions so engaged; and

a supporting structure for maintaining said blade adjusting member andsaid diaphragm member in predetermined relation to one another.

2. The invention defined by claim 1 in which said onepiece diaphragmmember is formed of resilient sheet metal material.

3. The invention defined by claim 1 in which said peripheral strapmember comprises an elongate web supported in substantially circularform by said supporting structure, said blade support means comprisingflexible arm members extending outwardly from said web in generallytangential relation thereto when said web is so supported.

4. An iris diaphragm unit adapted to define an aperture of variable sizein concentric relation to a predetermined axis, said unit comprising:

a generally circular support member surrounding said axis;

a plurality of partially overlapping diaphragm blades extending inwardlyfrom said support member past said axis;

flexible means integral with one end of each of said blades, saidflexible means being attached respectively to said support member atequiangularly spaced points thereof equidistant from said axis;

an adjusting member adjacent said blades and angularly revolvable aboutsaid axis, said adjusting member including blade control means spacedthereon in equiangular concentric relation to said axis and engageablerespectively with the ends of corresponding ones of said blades oppositethe ends thereof integral with said flexible means; and

means for angularly revolving said adjusting member to vary selectivelythe aperture defined about said axis between portions of said bladesadjacent thereto.

'5. A one-piece iris diaphragm member comprising:

an elongate continuous support strap;

a plurality of flexible blade support arms having first portionsintegral with said strap at spaced positions along said strap, said armsfurther having second portions in parallel relation to said strap; and

a corresponding plurality of diaphragm blades integral with respectivesecond portions of said arms and extending transversely of said armswith said blades disposed in substantially the same plane.

6. The invention according to claim 5 wherein said strap is of asubstantially uniform cross secti n h oughout its length.

7. An iris diaphragm comprising:

a tubular support member;

a plurality of diaphragm blades provided with flexible means integraltherewith and attached to said support member at symmetrically disposedpoints thereof, said blades being thereby movably supported transverselyof said support member in overlapping cooperating relation to define anaperture about the axis of said member; and

means for moving said blades in unison by flexing said flexible means toalter selectively the size of the aperture defined by said blades.

8. A one-piece iris diaphragm comprising:

a generally circular support strap of substantially uniform crosssection throughout its length;

a plurality of diaphragm blades extending transversely of said supportstrap; and

blade support means for connecting each blade to said support strap,said support means comprising a flexible element having one partintegral with one end of said blade and another part integral with saidsupport strap.

9. The invention according to claim 8 wherein said circular supportstrap forms a substantially cylindrical member, and said blades extendgenerally inwardly of said cylindrical member.

10. A one-piece iris diaphragm member comprising an elongate strapmember of substantially uniform cross section throughout its length andincluding a plurality of flexible hinge members integral therewith atuniformly spaced positions along said strap member, a plurality ofdiaphragm blade members, each of said hinge members being integral witha corresponding diaphragm blade member, said blade members adapted tocooperate in overlapping relation to define an aperture variable in sizein accordance with the relative positions of said blade members.

11. The invention according to claim 10 and further including a supportring for said strap member With said strap member supported to form asubstantially cylindrical member, and said blades extend generallyinwardly of said cylindrical member.

12. In an iris diaphragm comprising:

a support member;

an adjusting member revolvably adjustable in coaxial relation to saidsupport member;

a plurality of diaphragm blades engaged at opposite ends thereof withsaid support member and said adjusting member respectively andpositioned thereby in symmetrical overlapping relation to one another todefine about the axis of said members an aperture variable in size inaccordance with the adjustment of said adjusting member; the improvementcomprising;

resilient members integral with said blades for movably attaching eachof said blades to said support member and for biasing said blades towardpredetermined corresponding positions thereof at which said blades arein predetermined overlapping symmetrical relation to one another.

13. An iris diaphragm member comprising a single piece of resilientsheet metal material formed to define:

a support strap of substantially uniform cross section throughout itslength;

a plurality of resilient arms integral with and extending from saidstrap in spaced relation therealong; and

a plurality of diaphragm blades, each of which is integral with acorresponding one of said arms and movably connected to said strapthereby.

14. The invention according to claim 13 and further including a supportring for said strap member with said strap member supported to form asubstantially cylindrical member, and said blades extend generallyinwardly of said cylindrical member.

References Cited UNITED STATES PATENTS 3,005,395 10/1961 Mann -64-3,136,236 6/1964 Hart] 95-64 3,348,463 10/1967 Nerwin 9564 NORTONANSHER, Primary Examiner JOSEPH F. PETERS, JR., Assistant Examiner

